libata: implement dump_id force param

Add dump_id libata.force parameter.  If specified, libata dumps full
IDENTIFY data during device configuration.  This is to aid debugging.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Larry Baker <baker@usgs.gov>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

3 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b56ea860da21..a5c055066764 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1252,6 +1252,8 @@ and is between 256 and 4096 characters. It is defined in the file
                         * nohrst, nosrst, norst: suppress hard, soft
                           and both resets.
 
+                        * dump_id: dump IDENTIFY data.
+
                         If there are multiple matching configurations changing
                         the same attribute, the last one is used.
 
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8959f42c5b3b..06b7e49e039c 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2126,6 +2126,14 @@ retry:
                 goto err_out;
         }
 
+        if (dev->horkage & ATA_HORKAGE_DUMP_ID) {
+                ata_dev_printk(dev, KERN_DEBUG, "dumping IDENTIFY data, "
+                               "class=%d may_fallback=%d tried_spinup=%d\n",
+                               class, may_fallback, tried_spinup);
+                print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET,
+                               16, 2, id, ATA_ID_WORDS * sizeof(*id), true);
+        }
+
         /* Falling back doesn't make sense if ID data was read
          * successfully at least once.
          */
@@ -6377,6 +6385,7 @@ static int __init ata_parse_force_one(char **cur,
                 { "3.0Gbps",    .spd_limit      = 2 },
                 { "noncq",      .horkage_on     = ATA_HORKAGE_NONCQ },
                 { "ncq",        .horkage_off    = ATA_HORKAGE_NONCQ },
+                { "dump_id",    .horkage_on     = ATA_HORKAGE_DUMP_ID },
                 { "pio0",       .xfer_mask      = 1 << (ATA_SHIFT_PIO + 0) },
                 { "pio1",       .xfer_mask      = 1 << (ATA_SHIFT_PIO + 1) },
                 { "pio2",       .xfer_mask      = 1 << (ATA_SHIFT_PIO + 2) },
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 4c5eca4e663b..3bad2701bfa6 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -386,6 +386,7 @@ enum {
         ATA_HORKAGE_1_5_GBPS    = (1 << 13),    /* force 1.5 Gbps */
         ATA_HORKAGE_NOSETXFER   = (1 << 14),    /* skip SETXFER, SATA only */
         ATA_HORKAGE_BROKEN_FPDMA_AA     = (1 << 15),    /* skip AA */
+        ATA_HORKAGE_DUMP_ID     = (1 << 16),    /* dump IDENTIFY data */
 
          /* DMA mask for user DMA control: User visible values; DO NOT
             renumber */